A radio communications method includes carrying out, by a transmitter: providing a digital time signal carrying digital symbols to be transmitted; and transmitting a radio frequency signal carrying the digital time signal. The method further includes carrying out, by a receiver: receiving the radio frequency signal transmitted by the transmitter; processing the received radio frequency signal to obtain a corresponding incoming digital signal; and extracting, from the incoming digital signal, the digital symbols carried by the incoming digital signal. The digital time signal carrying the digital symbols to be transmitted results from an approximation of the Hilbert transform in frequency domain, which approximation is based on a frequency main mode and one or more frequency twisted modes, wherein the frequency main and twisted modes carry, each, respective digital symbols to be transmitted.

A transmission device that improves data reception quality includes: a weighting synthesizer that generates a first precoded signal and a second precoded signal from a first baseband signal and a second baseband signal, respectively; a phase changer that applies a phase change of i to the second precoded signal; an inserter that inserts a pilot signal into the second precoded signal applied with the phase change; and a phase changer that applies a phase change to the second precoded signal applied with the phase change and inserted with the pilot signal. satisfies /2 radians<< radians or radians<<3/2 radians. Each of the first baseband signal and the second baseband signal is modulated via a modulation scheme of quadrature amplitude modulation (QAM) using non-uniform mapping.

Provided are a DFT-spread OFDM transmitter and transmission method and a DFT-spread OFDM receiver and reception method capable of receiving the transmitted signal with a frequency domain spectrum shaping vector designed to easily trade off PAPR for spectral efficiency without inter-symbol interference, the DFT-spread OFDM transmitter including a phase shifter for generating a pi/2 PAM symbol vector by phase-shifting a symbol vector including M PAM symbols, a DFT spreader for generating a DFT-spread pi/2 PAM symbol vector by spreading the pi/2 PAM symbol vector using an M-point DFT matrix, a frequency domain spectrum shaper for generating a frequency domain spectrum shaped pi/2 PAM symbol vector by multiplying each element of the DFT-spread pi/2 PAM symbol vector by each element of a first shaping vector including one or more zero (0) elements, and a sub-carrier allocator for allocating a non-zero element in the frequency domain spectrum shaped pi/2 PAM symbol vector to a sub-carrier in an allocated frequency range

Certain aspects of the present disclosure provide techniques for interference management reference signal (RS) transmission. An example method, performed at a first network entity, generally includes applying a frequency domain function to a first copy of a first reference signal (RS) sequence to obtain a modified first copy of the first RS sequence, and outputting, to a second network entity, frequency domain samples of the modified first copy of the first RS sequence and frequency domain samples of a second copy of the first RS sequence.

A data transmission method includes transmitting to-be-transmitted data in N frequency domain resource blocks, where each of the N frequency domain resource blocks includes K(n) subcarriers, where n=1, 2, . . . , N, N is greater than or equal to 1, and K(n) is greater than or equal to 1; performing inverse Fourier transform and an upsampling operation on the to-be-transmitted data in each of the N frequency domain resource blocks to form N groups of data sequences; and transmitting the N groups of data sequences.

Systems and methods are disclosed for producing a cyclically generated, continuous-phase, frequency-shift keying (CG-CPFSK) waveform which may be used for wired and/or wireless communication systems. Such waveforms may have a substantially constant modulus and have an underlying cyclic phase structure. Systems and methods are also disclosed for generating a waveform based on a cyclically continuous signal which may be subsequently translated into a radio frequency for transmission.

A system and method of variable latency data transmission. The method includes transforming a first original data frame in accordance with a first time-frequency transformation so as to provide a first transformed data frame wherein the first time-frequency transformation is associated with a first latency. The method further includes transforming a second original data frame in accordance with a second time-frequency transformation so as to provide a second transformed data frame wherein the second time-frequency transformation is associated with a second latency. Using a transmitter, elements of the first transformed data frame are transmitted over a first frame period corresponding to the first latency and elements of the second transformed data frame are transmitted over a second frame period corresponding to the second latency wherein the first frame period is different from the second frame period.

A device and method for signal separation in an orthogonal time frequency space communication system using MIMO antenna arrays. The communication device includes an antenna arrangement and a receiver. The receiver is configured to receive, from the antenna arrangement, a plurality of pilot signals associated with respective locations in a time-frequency plane wherein the plurality of pilot signals were transmitted from a corresponding plurality of transmit antenna elements. The receiver is further configured to receive signal energy transmitted by the plurality of transmit antenna elements and to measure, based upon the plurality of pilot signals, a plurality of two-dimensional time-frequency coupling channels between the plurality of transmit antenna elements and the antenna arrangement. The receiver is also operative to invert a representation of each of the plurality of two-dimensional time-frequency coupling channels to provide a plurality of inverted channel representations.

A method of implementing Orbital Angular Momentum (OAM) for radio communications in general and LTE in particular. Common prior art so far recreate the vorticity (axial rotation of the Poynting vector) by using ring-shaped antenna arrays. This application proposes to create the vorticity in signal processing without the need of any space diversity (i.e. work with a single antenna). An Hilbert transform is applied in frequency domain to the Fourier transform of the analytical representation of a band-limited OFDM signal. The Hilbert transform is then approximated by a development in series into orthogonal twisted modes. This can be seen as an inverse Fourier transform of the complex analytical signal. Therefore an OAM IFFT based transmitter is proposed where parallel IFFTs are performed for each OAM mode and superimposed.

Provided are an apparatus and a method for processing signal in a multiple access mobile communication system based on multiple beams, and a multiple access mobile communication system based on multiple beams. The apparatus includes: a modulating unit modulating a common control signal and a traffic data signal to be transmitted to a plurality of respective communication terminals; a mapping unit mapping the common control signal and the traffic data signal modulated by the modulating unit to subcarriers, respectively; a phase shifting unit phase-shifting the common control signal mapped to the subcarrier as long as a delay time designated to correspond to the plurality of communication terminals; and a Fourier transforming unit generating a transmission signal corresponding to each communication terminal by Fourier-transforming the respective subcarriers to which the common control signal and the traffic data signal phase-shifted as long as the designated delay time are mapped.